Definition of Intestine, small

Intestine, small: The tubelike organ that
receives the products of digestion from the stomach. It has
three parts, the duodenum, the jejunum, and the ileum. The
duodenum is rich in glands that produce digestive enzymes,
and also receives bile from the liver. Digested material
moves from the duodenum to the ileum through the jejunum.
The ileum ends with the ileocecal valve, which prevents
food passed into the large intestine from traveling back
into the small intestine. The walls of the small intestine
are muscular, and contract to move digested food along its
length. The intestinal tube is lined with a mucus-like
tissue that sends forth tiny, finger-like projections
called villi. The villi increase the surface available for
absorbing nutrients from digested food.